This invention relates generally to the field of devices for the transport of therapeutic or biological molecules into and across skin tissue barriers, such as for drug delivery.
Drugs are commonly administered today through either the oral, parenteral, or transdermal routes of administration. One great challenge to transdermal administration is poor permeation of the active agent through the skin. The rate of diffusion depends in part on the size and hydrophilicity of the drug molecules and the concentration gradient across the stratum corneum. Few drugs have the necessary physiochemical properties to be effectively delivered through the skin by passive diffusion, iontophoresis, electroporation, ultrasound, chemical permeation enhancers, and heat (so-called active systems) have been used in an attempt to improve the rate of delivery. Furthermore, the combination of the active agent, permeation enhancers, and certain carriers have been used in order to try and achieve specific delivery profiles over a desired duration.